This invention relates generally to the manufacture of semiconductor devices, and more particularly to apparatus for use in Liquid Phase Epitaxial (LPE) deposition processes.
In the mass production of semiconductor devices, it is often required that large numbers of semiconductor wafers be subjected to LPE deposition. In the prior art, it was typical that many wafers were exposed to a liquid melt containing the source to be deposited at the same time. It was therefore necessary to utilize a very large melt area, or alternately, to divide the melt into a number of portions equal to the number of wafers on which deposition was to occur. This latter scheme is often referred to as the Aliquot technique. Both of these prior art deposition methods required a fixture of physical size much greater than is required for deposition upon a single wafer. To dissolve the source material in the melt, the fixture had to be placed in a relatively large heating furnace. However, it is very difficult to achieve a uniform temperature profile over a very large fixture. Furthermore, during the LPE deposition process, the temperature in the furnace must be rapidly decreased, which is more difficult to achieve in a large furnace than in a smaller one.
It is therefore an object of the present invention to provide a serially operative liquid phase epitaxial reactor in which wafers may be stacked before and after epitaxial growth to minimize the required reactor and furnace size.
It is a further object of the invention to provide a liquid phase epitaxial reactor in which a simple cycling mechanism induces feeding of the wafers into the melt region and extraction of the wafers from the melt region.